Phase transition kinetics of superionic H 2 O ice phases revealed by Megahertz X-ray free-electron laser-heating experiments by Husband, RJ, Liermann, HP, McHardy, JD, McWilliams, RS, Goncharov, AF, Prakapenka, VB, Edmund, E, Chariton, S, Konôpková, Z, Strohm, C, Sanchez-Valle, C, Frost, M, Andriambariarijaona, L, Appel, K, Baehtz, C, Ball, OB, Briggs, R, Buchen, J, Cerantola, V, Choi, J, Coleman, AL, Cynn, H, Dwivedi, A, Graafsma, H, Koemets, E, Marquardt, H